The long-term objective of this proposed research is to offer to hospitals and large group practices a fast, accurate, safe, painless, and inexpensive device for diagnosing cystic fibrosis in patients of any age. Our technique is spectroscopic in situ analysis sweat. Phase I or our research plan is intended to produce a clinical protorype of our device. This research plan is an outgrowth of earlier research which produced the governing theory and laboratory equipment. Phase I objectives include the optimization of our technique and equipment, and the resolution of remaining questions. The specific aims of Phase I research are the development of an optimized power supply, photomultiplier detector, computer control system, glass electrode, portable cart, and the chemical analysis of sweat induced by the system. After Phase I research is completed and a clinical prototype is produced, a clinical testing period will follow under a separate research agenda. The results of this testing will provide the basis for Phase II work. Phase II research and development will result in a commercial version of the in situ spectroscopic device which will then be offered to hospitals and group practices for the routine screening and diagnosis of cystic fibrosis.